The field of art to which this invention pertains is animal litter compositions.
In order to be useful in animal litter, materials must have good water or moisture absorbency and should have the capacity to eliminate or substantially reduce odors, particularly ammonical odors which normally result from animal waste.
Various clays, such as those based on the clay minerals kaolinite, illite, attapulgite, montmorillonite, sepiolite, diatonite, and the like, have been used extensively in animal litter compositions due to their water and moisture absorbing properties. However, such clays have very little, if any, deodorizing properties.
In U.S. Pat. No. 4,157,696, animal litter pellets which have moisture absorbency and deodorizing capability are made from flyash and cellulosic materials plus clays such as bentonite and kaolin.
U.S. Pat. No. 4,704,989 discloses pelletizing clay fines with deodorizers, bacteriocides, antioxidants and mold inhibitors to form cat box absorbents. Deodorizers, such as pine oil, wintergreen, sodium bicarbonate, chlorophyll, sodium dihydrogen phosphate, potassium dihydrogen phosphate, potassium acid phthalate, the water-soluble constituents of cherry pits, 2-isopropoxycamphane and 2(beta-hydroxy-ethoxy) camphane, are listed.
Animal litter compositions having deodorizing capability are described in U.S. Pat. No. 4,258,660. Such compositions are pellets of straw, sunflower hulls and dried alfalfa bound together with a bentonite clay.
In U.S. Pat. No. 4,914,066, moisture absorbent pellets useful as animal litter are made from a blend of bentonite clay and solid water-swellable but water-insoluble polymeric hydrocolloids.
Various processes for making water absorbent clay products are described in U.S. Pat. Nos. 4,591,581; 4,343,751; and 3,935,363.